1. Field of the Invention
The present invention relates to a defect inspection system that in a manufacture process for manufacturing an object by forming a pattern on a substrate, such as a semiconductor manufacture process, a liquid crystal display device manufacture process, and a printed circuit board manufacture process, inspects an occurrence status of a defect, such as a foreign substance, in manufacture steps of detecting a defect occurred, such as a foreign substance, analyzing it, and taking action, and a method therefor.
2. Description of the Related Art
In the conventional semiconductor manufacture process, if a foreign substance exists on a semiconductor substrate (an inspection subject substrate to be examined) it will become a failure cause of bad insulation of wiring, short circuit, etc. Further, if a semiconductor device becomes a very small and a minute foreign substance exists in the semiconductor substrate, this foreign substance might become a cause of bad insulation of a capacitor and breakage of a gate oxide film etc. Various causes give rise to these foreign substances and make them exist on the substrate in various states, such as occurring from a movable part of a conveyance apparatus, occurring from a human body, occurring by a reaction of a process gas in a processing system, or being mixed in chemicals and materials.
In a similar manufacture process of a liquid crystal display device, if any defect occurs, such as intermixing of a foreign substance on the pattern, the liquid crystal display device becomes unusable as a display device. A situation is the same also in the manufacture process of a printed circuit board; intermixing of a foreign substance becomes a cause of short circuit or poor connection of the pattern.
As one of conventional technologies of this kind of detecting the foreign substance on a substrate, there is a technology, as described in JP-A No. S62 (1987)-89336 (Patent document 1), that makes it possible to perform high-sensitivity and high-reliability foreign substance and defect inspection while eliminating a false report due to the pattern by detecting scattered light from a foreign substance that is occurred when the foreign substance adheres to a semiconductor substrate, by irradiating laser light onto the semiconductor substrate and by comparing it with an inspection result of a semiconductor substrate of the identical kind that was inspected just before this detection. Moreover, as disclosed by JP-A No. S63 (1988)-135848 (Patent document 2), there is a technique that detects scattered light from the foreign substance occurred in the case where the foreign substance adheres onto the semiconductor substrate by irradiating laser light on the semiconductor substrate, and analyzes the foreign substance so detected with a analysis technology, such as laser photoluminescence or secondary X-ray analysis (XMR).
Moreover, as a technique of inspecting the foreign substance, there is known a method where the inspection subject substrate is illuminated with coherent light, light emitted from a repeating pattern on the inspection subject substrate is removed by a spatial filter, and a foreign substance and a defect having no repeatability are emphasized and detected.
Moreover, JP-A No. H1 (1989)-117024 made a foreign substance inspection system to be known that irradiates illumination light to a circuit pattern formed on the inspection subject substrate from a direction inclined by 45° with respect to a main straight line group of the circuit pattern and prevents the zeroth order diffracted light from the main straight line group from entering into an aperture of the objective lens. In this conventional technology 3, the document also describes that other straight lines that are not main straight line group are shaded by a spatial filter.
In addition, as conventional technologies about defect inspection systems for foreign substances and the methods therefor, the following Patent documents are known: JP-A No. H1 (1989)-250847 (Patent document 4), JP-A No. H6 (1994)-258239 (Patent document 5), JP-A No. H6 (1994)-324003 (Patent document 6), JP-A No. H8 (1996)-210989 (Patent document 7), and JP-A No. H8 (1996)-271437 (Patent document 8).
Furthermore, U.S. Pat. No. 5,822,055 (Patent document 9) made a defect inspection system and a method therefor to be known that detects a defect using a luminance difference between dies that are inspection results, respectively, by simultaneously performing the bright visual field illumination and the dark visual field illumination.
However, the conventional technologies of the Patent documents 1 to 8 have a problem that in an irregular circuit pattern part, a defect signal may be overlooked due to the scattered light from the pattern, which results in decreased sensitivity.
Although in the Patent document 9, high-accuracy alignment is realized by using a bright visual field image, in order to obtain contrast of the defect part in the bright visual field image, an image must be obtained in a small image size that is comparable to the defect size or a few times larger than it or less by increasing a magnification. For this reason, there is a problem that inspection area per unit time is small which decreases throughput. Moreover, since the bright visual field illumination and the dark visual field illumination illuminate the identical place simultaneously, a scattered light distribution occurred thereby is unique. Therefore, there is a problem that the scattered light distribution occurred by the bright visual field illumination and the scattered light distribution occurred by the dark visual field illumination cannot detect respective features individually. Furthermore, since only the luminance difference between dies in each detection result is used, there is a problem that optical characteristics other than it (polarization, phase, etc.) or features on the image (contrast etc.) cannot be detected.